Hosts often utilize what is known as Expansion Read Only Memory (Expansion ROM) in order to direct boot processes and enable an Operating System (OS) at the host to properly initialize. An Expansion ROM provides firmware boot instructions that are retrieved, for example, by a Basic Input/Output System (BIOS) of a host. A host BIOS can detect a PCIe device (e.g., an expansion card) that implements the Expansion ROM, and can access the expansion ROM via a PCIe link. The host BIOS can for example directly retrieve data from the Expansion ROM via PCIe read requests in order to acquire boot instructions needed by the OS.